Guys I had my 27 out yesterday and noticed a slight miss that wasn't there the day before. Was hardly noticeable until changing into top speed it jumped about and struggled to pull away.
Today I thought I would checks coils, plugs, timer & wires etc and found i couldn't get it to start at all, just a chug on each attempt.
I removed all plugs and lay on the head connected, key on Battery, hand cranked and checked the spark one by one, looked correct and engine cranked over smoothly. I then fitted a timer indicator to No 1 to check if the spark was adjusted correct, it was.
Next a compression test and found no compression in No 1 or No 2. I am hoping its just a blown head gasket, when I purchased the car in Feb it just had a valve repaired and the head gasket was sprayed with copper & reused.
Is there anything I should be aware off as I haven't replaced a head gasket yet?
I have a new silicon head gasket on hand which I purchased earlier, I have since read most people don't like them but its what i have on hand so its going on.
My T has a Z head. Approx what torque should I target on the head studs?
Any other advice on this issue will be appreciated
Kevin: Read the instructions for the head gasket you have. I think that they say DO NOT use on a Z head. Dan
Make sure you put the gasket on the correct way, the big water openings at either end are slightly different. Also, while you have the head off check/clean the small (1/4") steam holes in the block and the head.
Do a cylinder leakage test before you tear it apart. Put the cylinder to be tested on TDC compression stroke. Put the car in high gear and securely block the wheels. Apply compressed air, doesn't have to be full tank pressure. If you hear air coming out an adjacent spark plug hole, the head gasket is blown there. If it comes out the radiator, it's blown into the water jacket. If it comes out the carb or tail pipe, it's a valve. Anyway, you are going to have to pull the head, but knowing what the problem is beforehand would be good. You may just have a couple of sticky valves. Good luck
45 foot pounds is enough. Some people like 50-55f/lb but the later blocks strip threads easily so i normally avoid that much torque.
Dan your correct I just read the instructions and it says exactly that although it does tell you how to check before fitting...bugger.
Ken, Good idea I will check the steam holes etc
Erik I will try that test, wouldn't think two cylinder valves would stick on the same day but you never know.
Kep, thanks I will target 45lb. Do you get your head gaskets in NZ? I'm going to Pipeline tomorrow if you wanted me to try and find any fittings?
Ken, completed the air check and its coming out the No 2 cylinder as i hoped.
I've been trying to locate a gasket here in NZ with a reasonable price tag, no luck so far, I see Macs stock a steel gasket as well as the copper and reads the only issue you can only use once, that's fine and they are only $17. Has anybody tried these?
Before you pull the head take the valve cover off and look at the valves for the bad cylinders. They may just be hanging up and need a little lube or the valve gap adjustment is too tight and just needs to be re-gaped.
You can use a wood dowel and lightly tap them back down through the spark plug hole if they are sticking.
Kevin, I only use the steel clad gasket, Lang's part# 3002A, on aluminium T heads, sprayed copper sealer, never had any problems. Just remember to re-torque when the engine is completely cold.
Mark I'm sure its not valves but a good trick.
You might pull the head and see what is actually going on. Maybe you can fix it with the parts you have. Do you have a used head gasket that looks good?
Twice I have placed 2ed hand copper head gaskets (not from my car) on my engine and both times put many miles on my car. The one om my car now is the 2ed one. I did use copper coat on both which is why I had use the 2ed one. Oh, I did clean both gaskets with steel wool.
Ted, no I don't have any old gaskets. yes I will pull the head off and take a look. I'm interested to see if the pistons are alloy. Might order a couple of gaskets tonight. If I had a standard head I would fit that using the silicon gasket but looks like I'm off the road for about 3 weeks until parts arrive and it would be the car at the front of the row lol.
Make sure the bolts are not bottoming out in the holes. They should screw all the way down to the head with no gasket in place.
Re "head I would fit that using the silicon gasket" Why?
Unless your head and block are totally flat many people find them to be trouble. Copper gasket for the Z, copper or steel for the stock head.
Erik I will check the holes thanks,
Mark thanks, Why not steel using the Z? I have ordered both steel and copper so will decide at the time.
Kevin, I am in the middle of a project, the same as you basically. I just found out my head is also Aluminum, and had it milled down, to make sure it is flat and level. I have been told from day one, use a copper head gasket, for an Aluminum head with Lots of copper spray, on both sides of it, when installing it again. My belief is that the copper will mold itself between the head and block, along with the copper gasket spray, it should almost always guarantee a good seal, and help with the heat. Keith
About silicon gaskets like Lang's part #3002SIL - Lang's writes it won't work for high compression alu heads:
One of our chapter members proved that silicone gaskets don't work on Z heads by using one anyway. He nearly destroyed his engine when he drove it home with coolant leaking into a cylinder and contaminating his oil. Took 3 oil changes to finally get the remnants of the coolant out of his crankcase. Luckily, there was no apparent damage done to babbitt or cylinder walls. Very lucky.
I only use the sandwich type head gaskets once. I always start with a new one. But if your out and about you may have to reuse it. I always have an extra in a box on the shelf.
I was in town on Tuesday and found a can of copper spray for $33! That's 2 steel gaskets or 1 1/2 copper ones. I see its a lot cheaper in the US but they wont ship cans. At this stage I wont be using it.
They got by without copper spray for a long time. The current gasket was reused in Feb with copper spray following a valve repair so hopefully a new gasket without will last longer.
Kevin H, I thought I had a spare with the silicon on hand, I have 3 gaskets ordered.
Jerry that's a good lesson and Roger I think I purchased mine from Lang's and it has a warning label on the wrapping.
Being new to the game I didn't realize I had a Z head until after I had ordered it and then didn't realize it was not suitable until it was posted on this thread and I read the warning.
Frank van E uses Steel with Alloy head so not sure yet, I have a few weeks to ponder.
Kevin I would have replied as above that the copper is softer. Even copper will leave embed marks on the cast iron block. That's why the fire ring is put with the crimped side up, it's easier to fix the head then the block.
Good point Mark, thanks.